Copper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and... Show moreCopper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and the acute toxicity of spherical 50 nm copper nanoparticles was assessed in juvenile rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas) and zebrafish (Danio rerio) for in vivo aqueous exposures following standardized OECD 203 guideline tests. The fate of the CuNPs in the aqueous media was temperature dependent. At the higher study temperature (26 ± 1 C), there was both an enhanced particle aggregation and higher rate of dissolution compared with that at the lower study temperature (15 ± 1 C). 96 h LC50s of the CuNPs were 0.68 ± 0.15, 0.28 ± 0.04 and 0.22 ± 0.08 mg Cu/L for rainbow trout, fathead minnow and zebrafish, respectively. The 96 h lowest-observed-effect concentration (LOEC) for the CuNPs were 0.17, 0.023 and <0.023 mg/L for rainbow trout, fathead minnow, and zebrafish respectively, and are below the predicted environmental concentration of CuNPs for some aquatic environments suggesting a possible ecotoxicological risk to fish. Soluble copper was one of main drivers for the acute toxicity of the copper nanoparticles suspensions. Both CuNPs suspension and copper nitrate caused damage to gill filaments and gill pavement cells, with differences in sensitivity for these effects between the fish species studied. We show therefore common toxicological effects of CuNPs in different fish species but with differences in sensitivity with implications for hazard extrapolation between fish species. Show less
Treatment for advanced colorectal cancer (ACC) consists primarily of systemic treatment, mostly without curative intent. Systemic therapies are associated with potentially severe side effects.... Show moreTreatment for advanced colorectal cancer (ACC) consists primarily of systemic treatment, mostly without curative intent. Systemic therapies are associated with potentially severe side effects. Furthermore, treatment is not effective in all patients. Currently, pre-treatment predictors for efficacy and toxicity in systemic treatment of ACC are scarce. Germline genetic variation in genes encoding for enzymes involved in pharmacokinetics or pharmacodynamics of cytotoxic drugs could explain intra-patient differences in treatment effects. Pharmacogenetic studies aim at finding such germline genetic predictors. This thesis focusses on pharmacogenetics of capecitabine and oxaliplatin in treatment of ACC. First, it is established that results derived from DNA in archived tumor samples can be reliably compared to those using DNA from peripheral blood leukocytes. Then, germline genetic markers in MTHFR and MTRR, as well as markers derived from an in vitro genome-wide association study (GWAS) are tested for their association with capecitabine toxicity. Next, effects of ERCC1 genotype on oxaliplatin cytotoxicity in vitro and in clinical association analysis are addressed. The influence of genetic variation in organic cation transporters on oxaliplatin-induced neurotoxicity is examined. Lastly, the results of a GWAS searching for germline predictors of treatment efficacy of capecitabine, oxaliplatin and bevacizumab, with or without cetuximab, are presented. Show less
This thesis focuses on the implications of empirical evidence generation for the evaluation of safety and toxicity during drug development. A shift in paradigm is proposed to 1) ensure that... Show moreThis thesis focuses on the implications of empirical evidence generation for the evaluation of safety and toxicity during drug development. A shift in paradigm is proposed to 1) ensure that pharmacological concepts are incorporated into the evaluation of safety and toxicity; 2) facilitate the integration of historical evidence and thereby the translation of findings across species; and 3) promote the use of experimental protocols tailored to address specific safety and toxicity questions. Nonlinear-mixed effects modelling is recommended as a tool to account for such requirements. Our goal was to explore the feasibility of a model-based approach to toxicology assessment and risk prediction in humans and, where possible, to compare the performance of this approach to traditional safety assessment approaches. The investigational plan of the thesis was divided into two sections where the development of methodology is followed by a case study with real data. A variety of analysis strategies and protocol designs are investigated where we set the constraint that proposals to deviate from existing protocols be minimal. We finally compile recommendations for protocol optimisation and data analysis/interpretation strategies to facilitate the implementation of model-based techniques in safety pharmacology and toxicology research Show less
Metals in soils can pose a serious threat to soil dwelling organisms, plants, and human beings. A major uncertainty in terrestrial ecological risk assessment for metals is theintegrated effect of... Show moreMetals in soils can pose a serious threat to soil dwelling organisms, plants, and human beings. A major uncertainty in terrestrial ecological risk assessment for metals is theintegrated effect of the physicochemical properties of soil on toxicity and how this allows for extrapolation of toxicity data across soils. The recognition that soil type is an important factor that determines metal toxicity, goes along with the increasing insight into bioavailability. There is a growing consensus that only a proportion of the total amount of metal in soil isavailable for uptake by organisms and subsequently induces toxic effects. Development of mechanistically underpinned approaches for explaining and predicting availability effects onmetal toxicity has been the subject of many research efforts in terrestrial ecotoxicology. Show less
Melanoma is a malignancy that arises from melanocytes, the pigment-producing cells that can be predominantly found in the eye or the epidermal basal layer of the skin. Mainly due to increased UV... Show moreMelanoma is a malignancy that arises from melanocytes, the pigment-producing cells that can be predominantly found in the eye or the epidermal basal layer of the skin. Mainly due to increased UV exposure, the incidence of melanoma has doubled worldwide over the past three decades (200.000 new cases in 2008). Primary melanomas can be easily treated by surgical resection, leading to a good prognosis for stage I patients. However, metastasized melanoma is almost completely resistant to therapeutic modalities such as radio- and chemotherapy, resulting in a median overall survival of less than one year for this patient group. Despite considerable efforts, for over 20 years there was no melanoma treatment developed that could improve survival of stage IV patients. However, the treatment of unresectable metastasized melanoma has progressed markedly in recent years due to the development of both immunotherapies that stimulate anti-tumor immunity and targeted therapies that block oncogenic proteins. This thesis will focus on pre-clinical work concerning the optimization of melanoma treatment. In detail, it will address for both targeted therapies and immunotherapies factors that play a role in the identification of response-predictive biomarkers, the toxicity of treatments, and the potential efficacy of combination treatments. Show less
Technological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in... Show moreTechnological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in applied biomedical research, using selected cases. We look at the use of zebrafish embryos as disease models, taking fetal alcohol syndrome and tuberculosis as examples. We discuss advances in imaging, in culture techniques (including microfluidics), and in drug delivery (including new techniques for the robotic injection of compounds into the egg). The use of zebrafish embryos in early stages of drug safety-screening is discussed. So too are the new behavioral assays that are being adapted from rodent research for use in zebrafish embryos, and which may become relevant in validating the effects of neuroactive compounds such as anxiolytics and antidepressants. Readouts, such as morphological screening and cardiac function, are examined. There are several drawbacks in the zebrafish model. One is its very rapid development, which means that screening with zebrafish is analogous to __screening on a run-away train.__ Therefore, we argue that zebrafish embryos need to be precisely staged when used in acute assays, so as to ensure a consistent window of developmental exposure. We believe that zebrafish embryo screens can be used in the pre-regulatory phases of drug development, although more validation studies are needed to overcome industry scepticism. Finally, the zebrafish poses no challenge to the position of rodent models: it is complementary to them, especially in early stages of drug research. Show less
Hoebers, F.; Heemsbergen, W.; Moor, S.; Lopez, M.; Klop, M.; Tesselaar, M.; Rasch, C. 2011
Purpose: To analyze the effectiveness and toxicity of reirradiation (re-RT) for head-and-neck cancer.Methods and Materials: A retrospective data analysis was performed of 58 patients who underwent... Show morePurpose: To analyze the effectiveness and toxicity of reirradiation (re-RT) for head-and-neck cancer.Methods and Materials: A retrospective data analysis was performed of 58 patients who underwent re-RT with curative intent. Re-RT was given as definitive treatment in 53% of patients, whereas salvage surgery preceded reirradiation in 47%. The median cumulative RT dose was 119 Gy (range, 76-140). Concurrent chemotherapy was administered with re-RT (CRT) in 57% of patients. Event-free survival was defined as survival without recurrence and without serious toxicity (>= Grade 3).Results: Median follow-up was 57 months (range, 9-140). Locoregional (LR) control was 50% at 2 and 5 years. The 2-year and 5-year overall survival (OS) was 42% and 34%. The following factors were associated with improved OS: postoperative re-RT (vs. primary re-RT), treatment with RT only (vs. CRT) and interval >3 years between previous RT and re-RT. For patients treated with postoperative re-RT and definitive re-RT, the 5-year OS was 49% and 20%, respectively. Patients treated with CRT had a 5-year OS of 13%. Serious (late) toxicity >= Grade 3 was observed in 20 of 47 evaluable patients (43%). Three cases of treatment-related death were recorded. The 2-and 5-year serious toxicity-free interval was 59% and 55%, respectively. Associated with increased risk of serious toxicity were CRT and higher re-RT dose. The event-free survival rates at 2 and 5 years were 34% and 31%, respectively.Conclusions: Re-RT in head-and-neck cancer is associated with poor survival rates of 13-20% in patients with inoperable disease treated with primary (chemo-) re-RT. For this subgroup, however, no other curative options are available. Long-term disease control and survival can be achieved in patients who receive re-RT as an adjunct to surgical resection. The rates of serious toxicity after re-RT are high, with an incidence of approximately 45% at 5 years. Approximately 1 in 3 patients survived re-RT without recurrence and severe complications. (c) 2011 Elsevier Inc. Show less
Environmental life cycle assessment (LCA) is a method for the quantitative assessment of the environmental impacts of products. A number of impact categories are related to toxic effects of... Show moreEnvironmental life cycle assessment (LCA) is a method for the quantitative assessment of the environmental impacts of products. A number of impact categories are related to toxic effects of chemicals. Multimedia models for substance fate, supplemented with models for human exposure, have been developed in the context of human and environmental risk assessment (HERA). Different authors have adapted such models for use in LCA, largely on a continental level. It has sometimes been suggested to merge LCA toxicity assessment and HERA into one common tool. Here, it is demonstrated that LCA and HERA cannot be merged, due to a fundamental difference concerning their respective goals. Subsequently, adaptations to existing multimedia models are proposed to make it possible to extend multimedia models with a module for metals. The core of the thesis is formed by the GLOBOX model: a global, regionally differentiated fate, intake and effect model for LCA toxicity assessment. For emissions of any organic chemical or metal to any compartment in any country or at any sea, this model calculates region-specific characterisation factors. Finally, an updated set of LCA normalisation factors is provided, with which the relative contributions of a product to the different impact categories can be evaluated. Show less
In this thesis, we focus on the palliative treatment of advanced colorectal carcinoma with capecitabine, irinotecan and oxaliplatin. We investigated the potential associations of germline genetic... Show moreIn this thesis, we focus on the palliative treatment of advanced colorectal carcinoma with capecitabine, irinotecan and oxaliplatin. We investigated the potential associations of germline genetic variations with the efficacy or toxicity of treatment. We genotyped a selection of SNPs in paired tumor tissue and blood samples of colorectal cancer patients (Chapter 3). Next, we present an overview of clinical and pharmacogenetic factors that have been described to influence irinotecan toxicity (Chapter 4). We investigated the association of febrile neutropenia and drug efficacy with the UGT1A1 genotype in Chapter 5. In Chapter 6, we investigated the GSTP1 Ile105Val SNP with regard to irinotecan efficacy in terms of progression-free survival. We also provide an overview of pharmacogenetic, pharmacokinetic and pharmacodynamic data on this platinum derivative (Chapter 7). In Chapter 8, we transfected ERCC1 negative cells with an ERCC1 gene, containing either the codon 118C or 118T genotype, in order to establish differences in cell survival or DNA repair. In chapter 9 we describe our investigations on the cumulative neurotoxicity and efficacy of oxaliplatin. In chapter 10, an explorative study is described that investigates associations of survival and toxicity in patients receiving oxaliplatin, using a SNP array. Show less
